Escapement-initiating mechanism for typewriter

ABSTRACT

An escapement mechanism is disclosed which initiates the escapement action at an earlier point in each cycle than prior art devices and which has a reduced tendency to slow the typebar on its way to the printing position. A linkage is provided between the ribbon lift structure and the escapement structure for initiating an escapement by the same action that initiates the ribbon lift and with the power provided directly from the power roll. The invention eliminates the need for the familiar &#39;&#39;&#39;&#39;U-bar.&#39;&#39;&#39;&#39; A spring is provided in the throat of the typebar guide for reducing the typebar velocity to an optimum value just prior to impact. The same spring also returns energy to the typebar to accelerate it to its rest position and thereby reduce the elapsed time per cycle of operation.

United States Patent Allen Feb. 29, 1972 [54] ESCAPEMENT-INITIATINGMECHANISM FOR TYPE'WRITER [21 1 Appl. No.: 880,820

[52] US. Cl. ..197/97, 197/17, 197/43, 197/157, 197/159, 197/183 [51]Int. Cl. 19/54 [58] Fieldofsearch ..197/17,43,82,97,151,157, 197/158,159, 183

[56] References Cited UNITED STATES PATENTS 713,703 11/1902 Smith..197/43 786,056 3/1905 Secor... .....l97/43 958,573 5/1910 Yaw 197/157969,530 9/ 1910 Eggebrecht t. 197/97 1,937,048 11/1933 Thompson et a1.197/159 1,950,761 3/1934 Thompson ..197/82 1,950,762 3/1934 Thompson197/157 1,969,411 8/1934 Miller 1 ..197/43 1,987,276 1/1935 Thompson197/17 UX 2,076,746 4/1937 Rowland et a1 ..197/97 2,156,001 4/1939Thompson ..197/97 X FOREIGN PATENTS OR APPLICATIONS 472,085 7/1914France ..197/43 219,994 1/1925 GreatBritain ..197/183 PrimaryExaminer-Ernest T. Wright, Jr. Attorney-George W. Killian, Charles R.Lepchinsky and Jay M. Cantor [57] ABSTRACT An escapement mechanism isdisclosed which initiates the escapement action at an earlier point ineach cycle than prior art devices and which has a reduced tendency toslow the typebar on its way to the printing position. A linkage isprovided between the ribbon lift structure and the escapement structurefor initiating an escapement by the same action that initiates theribbon lift and with the power provided directly from the power roll.The invention eliminates the need for the familiar U-bar. A spring isprovided in the throat of the typebar guide for reducing the typebarvelocity to an optimum value just prior to impact. The same spring alsoreturns energy to the typebar to accelerate it to its rest position andthereby reduce the elapsed time per cycle of operation.

1 Claims, 4 Drawing Figures PATENTEDFEB 29 I972 SHEET 1 0F 2 INVENTORRICHARD W. ALLEN MWJCLZLN AGE/VT PATENTEDFEB29 I912 3,645,374

SHEET 2 [IF 2 INVENTO/P RICHARD W. ALLEN AGENT ESCAPEMENT-INITIATINGMECHANISM FOR TYPEWRITER BACKGROUND OF THE INVENTION Ever since theintroduction of character-by-character printers, there has been a needto initiate a character escapement motion for each character printed.Some mechanisms provide for the escapement action at the conclusion ofprinting a character while other mechanisms provide an escapement actionprior to the printing of a character. In addition to providing anescapement action for each character, it is also necessary to provide anescapement action after each word or at any other place where it isdesired to provide a character space on the document. A space bar isnormally provided to manually generate interword spaces.

It has been standard typewriter design practice for many decades toprovide an element known as a U-bar as part of the mechanism forproducing an escapement, or word-spacing, action. The U-bar" is so namedbecause it has the general shape of the letter U and because it is alsoappropriately called a universal bar. The U-bar is so arranged in thetype basket that the action of any one of the plurality of typebars willstrike the U-bar" during the printing cycle. The striking of the U-barcauses the bar to move and the movement of the bar initiates anescapement action. A typical U- bar is approximately the size of thethumb and forefinger, when positioned to form a U." Each type bar willstrike the U-bar in a unique location and accordingly, the bar may bestruck nearly anywhere along one edge. In response to being struck by atypebar, the U-bar must move from its plane of rest to a substantiallyparallel plane. That is, ideally the motion of the U-bar" is independentof where it is struck or of which typebar initiated the action. It iswell known to those familiar with this or similar mechanisms, that aspecial construction and mounting of the U-bar is required to providethe desired parallel motion of the U-bar." Accordingly, several partsare required and the mass that must be moved once per printing cycle issubstantial. To move the required mass there must be sufficient energyin the typebar. This means that the typebar must have more mass thanmight otherwise be required and/or that it must be moved faster. Inaddition, it is well known that poor U-bar adjustment can result in aderogation of print quality.

It is an object of the present invention to eliminate the U- bar and theattendant disadvantages.

It is another object of the invention to provide a new and improvedstructure for transmitting an escapement initiating signal to theescapement mechanism.

It is another object of the invention to provide a new and improvedstructure for transmitting an escapement initiating signal to theescapement mechanism which is more economical, and easier to adjust andmaintain.

It is another object of the invention to provide an escapementinitiating structure which has a reduced tendency to derogate printquality.

It is another object of the invention to provide an escapementinitiating structure which does not introduce a variable factor into theprinting quality.

It is a more specific object of this invention to initiate an escapementaction in response to the operation of the ribbon lift mechanism.

It is yet another object of the invention to obtain an increasedprinting rate.

It is another object of the invention to provide a uniform andconsistently acting means for controlling the ultimate velocity of atypebar just prior to printing impact.

lt is yet another object of the invention to provide a structure whichinitiates the escapement action at an earlier point in the cycle andthereby reduces the tendency to print before the escapement action iscomplete.

SUMMARY OF THE INVENTION The present invention finds utility in anapparatus such as a character-by-character printer as exemplified by theubiquitous typewriter and encompasses the replacement of the standardU-bar" structure with a simple connecting link mechanism. Morespecifically, the invention comprises a modification of a standardstructure which includes a ribbon lift mechanism and an escapementmechanism. A connecting link is provided between elements of the twomechanisms so that a ribbon lift action produces or initiates anescapement action. The reverse is not true. That is, an escapementaction that is not responsive to a ribbon lift action does not initiatea ribbon lift action. The elimination of the U-bar" means that theflight time of the typebar is not slowed down as a result of contactbetween the two and therefore, the total flight time may be reducedthereby permitting an increase in printing rate. To provide goodimpression control, it is necessary to control typebar speed at impact.The old U-bar was used, in part, to control typebar speed. Now, with theelimination of the U-bar a flat spring at the throat of the typebarguide controls typebar speed and exercises its control at a later pointin the cycle thereby allowing the typebar to achieve its ultimateprinting position in a reduced time.

BRIEF DESCRIPTION OF THE DRAWING The drawing of the invention disclosedin this application comprises four figures wherein:

FIG. 1 illustrates the essential elements incorporated in a power-driventypewriter for initiating an escapement action in response to a printingcycle or the operation of the space bar;

FIG. 2 is a cross section view including many of the elements includedin FIG 1 and showing the manner in which the printing action initiatesboth the ribbon lift and the escapement action;

FIG. 3 illustrates the typebar guide and the associated spring forabsorbing some of the excess energy of a typebar; and

FIG. 4 shows the engagement of the typebar, typebar guide and controlspring when the typebar is in printing position.

It is believed that the invention may be fully comprehended byconsidering the drawing together with the following description of apreferred embodiment of the invention.

The present application discloses an improvement for use in theoperation and structure of power-driven typewriters and the inventionwill be disclosed and described as used in a typicalcharacter-by-character typebar page printer. Such printers are old andwell known in the art and therefore will not be disclosed in theirentirety in this application. For example, U.S. Pat. No. 2,700,446issued to E. O. Blodgett on Jan. 25, 1955, discloses a tape-controlledtypewriter of the type in which the present invention might be used.Particular attention is invited to FIG. 3 of the cited patent whereinthere is shown a power roller 21 and the linkage that is employed tomove typebar 36 to the printing position. Attention is also invited toUS. Pat. No. 3,355,000, issued to E. O. Blodgett on Nov. 28, 1967,wherein FIG. 1 is similar to FIG. 3 of the first-cited patent. Attentionis also invited to FIG. 15 of US. Pat. No. 2,797,790, issued on July 2,7 to E. O. Blodgett. This last named patent illustrates in FIG. 15thereof part of the mechanism for lifting a ribbon in response to eachtypebar action.

As is well known in the art, there must be a letter-spacing escapementaction for each character that is printed. The two earlier Blodgettpatents disclose some details of an escapement mechanism. Additionaldetails are well known and/or may be seen in various manufacturerspublications such as Friden Systems Flexowriter Operation and AdjustmentManual, Copyright 1961 and published by Friden, Inc. (now The SingerCompany, Friden Division, San Leandro, California). In addition, anescapement mechanism is shown in the copending application of R. W.Allen, filed May 21, 1969 and assigned Ser. No. 826,539 and assigned tothe same assignee as the present application.

As may be seen from FIG. 1 of the cited Blodgett U.S. Pat. No.3,355,000, the linkage for raising the typebar 36 to print impressionposition may include two bellcranks 34a and 34b. When bellcrank 34a ispivoted in the counterclockwise direction about its pivot point 30, theuniversal ribbon lift bar 41 is pivoted in a clockwise direction aboutits pivot point (not designated in the cited patent). The structure ofthe present invention includes the ribbon lift bar 41 and the bellcrank340 as shown in U.S. Pat. No. 3,355,000.

FIG. 2 of this application illustrates part of the inventive concept andadditional details of the ribbon lift structure as shown in FIG. of U.S.Pat. No. 2,797,790. More specifically, the figure shows fixed framemembers 101, 102 and 103 which provide support for various parts. Forexample, frame member 103 provides a support and pivot for the ribbonlift bar 104 which corresponds to the element 41 of the U.S. Pat. No.3,355,000. The ribbon lift bar 104 is a long member which is seen incross section and which extends across a substantial portion of thewidth of the typewriter. A frame member (not shown) and similar to framemember 103 supports the far end of ribbon lift bar 104. 105 is the pivotand bearing for ribbon lift bar 104. Ribbon lift bar 104 is pivotedabout its pivot point 105 in response to the clockwise pivoting ofbellcrank lever 106 about its pivot point 107. Bellcrank lever 106corresponds to element 340 of cited U.S. Pat. No. 3,355,000. It shouldbe noted that FIG. 2 of this application and FIG. 1 of U.S. Pat. No.3,355,000 are viewed from opposite ends of the machine. Accordingly, acounterclockwise pivoting of element 34a in U.S. Pat. No. 3,355,000corresponds to a clockwise pivoting of bellcrank 106 of thisapplication.

Attached at the approximate midpoint along the length of the ribbon liftbar 104 is a ribbon lift control lever 108. One end of a ribbon liftcontrol plate link 109 is pivotally coupled at pivot point 110 to ribbonlift control lever 108. The other end of ribbon lift control plate link109 is pivotally connected at pivot 111 to a ribbon lift control plate112. The ribbon lift control plate 112 is pivotally coupled at pivotpoint 113 to frame member 102.

Pivotally connected at pivot point 1 14 of ribbon lift control lever 108is the right-hand end 117 of a connecting link 115. The connecting link115 is typically an adjustable link whose length may be increased orreduced, prior to assembly into the mechanism, by turning the left end116 relative to the right end 117. The end 116 is coupled to link 115 bya threaded connection. Such adjustable links are widely used in suchstructures and are familiar to those acquainted with the art. The leftend 116 of connecting link 1 15 is coupled to slot 1 18 ofescapement-actuating lever 1 19. The escapement-actuating lever 119 isfixed to escapement shaft 120 by setscrew 121 (see FIG. 1) or by otherappropriate means so that axial rotation of escapement shaft 120 willpivot the escapement actuating lever 119; or pivoting of theescapement-actuating lever 119 will rotate escapement shaft 120. Theescapement shaft 120 is suitably supported with bearings in frame member101 and/or other similar frame members (not shown) which are in linewith frame member 101.

Reference may now be had to FIG. 1 of the present application whichillustrates some of the elements shown in FIG. 2. More specifically,there is shown the ribbon lift bar 104, the ribbon lift control lever108, the connecting link 115, the escapement actuating lever 119, theescapement shaft 120 and other elements.

Rigidly affixed by setscrew 122 to the escapement shaft 120 for rotationtherewith is an escapement trip bellcrank assembly 123. As may be seenfrom FIG. 1, a counterclockwise rotation of the ribbon lift bar 104 willresult in a counterclockwise rotation of escapement shaft 120 andtherefore a counterclockwise rotation of escapement trip bellcrankassembly 123. A bent over portion 124 of escapement trip bellcrankassembly 123 is effective to engage escapement trip lever 125 which issupported for pivotal motion on machine screw 126 which in turn issupported by frame member 127. The clockwise pivoting of escapement triplever.125 about its pivotal support screw 126 will effect a rightwardmotion of escapement trip slide 128.

The escapement trip slide 128 of FIG. 1 corresponds to the equivalentelement 133 as shown in cited application Ser. No. 826,539 of R. W.Allen. Accordingly, the manner in which the rightward motion ofescapement trip slide 128 effects an escapement action may be seen froma study and analysis of the invention disclosed in application Ser. No.826,539.

The ribbon lift bar 104 is normally biased towards clockwise rotation bya tension spring 132 which is coupled between ribbon lift control lever108 and a frame member 133.

As already stated, there must be an escapement action for each characterthat is printed. In addition, it is necessary to provide an escapementaction at other times. The most obvious need is to provide an escapementin order to produce an interword space. Such escapement is normallyinitiated in response to the operation of a space bar 136. FIG. 1illustrates the principal elements which play a part in initiating anescapement to produce an interword space.

Depression of space bar 136 pivots the space bar keylever 137 and in themanner well known in the art, and/or as set forth in one or more of thecited references, the pivoting of the space bar keylever 137 causes thespace bar cam assembly 138 to be released so that cam 139 engages powerroll 140. The engagement of cam 139 with power roll 140 causes apivoting motion of space bar cam assembly 138 such that cam link 141 ispulled downward to pivot escapement bellcrank assembly 142 about pivotrod 107 in a clockwise direction. Cam link 141 is similar to connectinglink in that its length may be adjusted by means screw threads. Pivotrod 107 is suitably supported by frame members (not shown). The pivotalmotion of escapement bellcrank assembly 142 is transmitted to escapementshaft by means of link 144 acting on lever which is affixed toescapement shaft 120. That is, link 144 is pivotally coupled at end 143ato lever 145 and at the end 143b to escapement bellcrank assembly 142.Link 144 and its ends 143a and 143k are threaded together to providemeans of adjusting the length of link 144 as may be required. Therotation of escapement shaft 120 initiates an escapement action in thesame manner as previously described when it was shown that escapementshaft 120 was rotated in response to the pivotal motion of the ribbonlift bar 104. Lever 145 is affixed to escapement shaft 120 by setscrew146 or other appropriate means.

It should be noted that an escapement action in response to theoperation of space bar 136 does not cause a ribbon lift operation. Thatis, although the rotation of escapement shaft 120 causes a correspondingpivotal action of escapement actuating lever 119 the motion is nottransmitted to connecting link 115 because of the slot 1 18 inescapement-actuating lever 119. Various other means might have beenprovided to prevent a ribbon lift operation in response to an escapementinitiated by'operation of space bar 136. For example, the left end ofconnecting link 115 could have been slotted.

In a similar manner, it is desirable to eliminate the transmission ofpivotal motion from the lever 145 to escapement bellcrank assembly 142when escapement shaft 120 is rotated by escapement actuating lever 119.To this end the left hand clevis 143a of link 144 has a slot 147. Thus,the pivoting of lever 145 in response to the pivoting of escapementshaft 120 by the escapement actuating lever 1 19 causes the coupling pin148, which is an integral part of lever 145, to reciprocate in the slot147 There may be a slight pivotal motion of link 144 but no motion willbe transmitted to the space bar cam assembly 138. i

Returning now to FIG. 2, it will be seen that the pivoting of bellcranklever 106 about its pivot point 107 in the manner more fully explainedin the cited Blodgett U.S. Pat. No. 3,355,000, will pull on typebar link151 which is pivotally coupled to the bellcrank lever 106 at 152. Theother end of the typebar link 151 is pivotally coupled at point 153 ondependent arm 154 of the typebar 155 which is pivoted at 156.Accordingly, the clockwise pivoting of bellcrank lever 106 about pivot107 causes a counterclockwise pivoting of typebar 155 about pivot point156.

As is well known to those familiar with typebar page printers, thetypebar 155 carries a type slug 157 and a printing action takes placewhen the typebar 155 is pivoted towards the platen 158 and comes intocontact with a print ribbon (not shown) which is between the type slug157 and a document supported by the platen 158. To avoid confusion inthe drawing, the familiar print ribbon and document are not shown. Theprint ribbon (not shown) is supported and lifted by the cloth ribbonguide 160. The cloth ribbon guide 160 is raised in response to thepivoting of the ribbon lift bar 104 which causes the ribbon lift controlplate 112 to pivot about pivot point 113. By means which can be readilyvisualized from an examination of FIG. 2, or from a study of the detailsin one or more of the cited references, it will be seen that thepivoting of plate 112 will raise the ribbon guide 160. The ribbon guide160 is guided by a sliding coupling to the typebar guide 170.

In order to provide good print alignment it is customary to provide atypebar guide 170 which is more clearly shown in FIG. 3. The typebarguide 170 is rigidly mounted to the segment casting (not shown) and doesnot move except in connection with case shifting, all as is standardpractice in such machines. First and second bent over portions 171 oftypebar guide 170 combine to form a V slot for guiding the typebar 155to its ultimate position. For clarity in showing other parts, only oneof the bent over portions 171 is shown. However, it should be understoodthat bent over portion 171 and a mirror image thereof combine to form aV slot to align the typebar 155 and position the printed character atthe proper location on the document.

In addition to obtaining good character alignment, it is also necessaryto provide impression control. In the typewriting art, impressioncontrol refers to the quality of the impression of the character on thedocument. If the typebar 155 moves too fast, the type slug 157 may havetoo much momentum and there will be a tendency to emboss the paper. Someembossing is normal and can usually be felt on an original document bymoving ones fingers lightly across the back of the document. If theembossing is too heavy, the document may even be perforated. Too lightan impression will cause uneven print quality with many characters thatare not as dark as desired. Many factors enter into print quality andimpression. The factors include: the type of ribbon being used, thenature of the document on which the printing is being placed, the numberof carbon copies being made and the material of which the platen ismade. Although each of the factors mentioned plays a part in printquality they will not be considered further herein. Other factors whichaffect print quality and impression are: the geometry and mass ofselected parts, the printing area of the character being printed andvelocity of typebar just prior to impact for print impression. For themost part the factors mentioned in the last sentence are fixed and/orrelatively little control can be exercised over them, once the machineis built. However, it should be understood that all factors arecarefully considered during the design ofthe various parts.

The principal areas in which adjustment may be made to control printimpression and print quality, in a physical machine, include somecontrol of typebar velocity just prior to impact and the initialvelocity given to the typebar. US. Pat. No. 3,355,000, in column 5,thereof, presents some discussion concerning means for controllinginitial velocity and/or type impression force.

As may be readily understood, a high initial velocity of the typebar 155can result in too heavy an impression. However, high initial velocity isdesirable to increase the number of characters which may be printed in agiven unit of time. Accordingly, when there is any premium on a highprinting rate, there is a conflict of interest between printing rate andprinting quality. One solution of the dilemma has been to impart a highinitial velocity to the typebar and then, sometime before impact, reducethe velocity to an optimum value for a good impression. The U-bar whichhad been used in prior art devices to initiate an escapement action wasalso used to reduce the velocity of the typebar. However, the use of theU-bar presented at least two difficulties; first it did not actuniformly or consistently and second it introduced the slowing factor alittle earlier than might be desired. The present invention overcomesthese difficulties by eliminating the U-bar" of prior art devices andsubstitutes in its place a simple flat spring 172 which exercises moreuniform and consistent control over the typebar velocity and which alsoacts later in the flight of the typebar thereby permitting a netincrease in potential printing rate.

FIG. 3 illustrates the typebar guide which has bent over portion 171 toform a V slot for guiding a typebar 155 into final alignment forprinting. Shortly before printing impact portion 180 of the typebar 155is engaged by spring 172 which absorbs some of the energy of the typebar155 and reduces the velocity of the typebar 155 to an optimum value forproper impression. The spring 172 is securely mounted to the typebarguide 170 by a machine screw 173. The typebar guide 170 is securelymounted to the segment casting (not shown) by machine screws (notshown). .The spring 172 is shaped as shown in FIGS. 3 and 4 so that theimpact area 175 of spring 172 is adapted to be engaged by area oftypebar 155. In normal operation area 181 of typebar 155 will not engagebar 176 of the typebar guide 170.

It is apparent that each typebar 155, as it approaches the printposition, strikes the impact area 175 of spring 17 2 at substantiallythe same angle and that therefore the spring 172 excrcises a constantand consistent influence on the action of each typebar 155. The initialvelocity of the typebar 155 may be controlled by various means familiarto those skilled in the art. As an example of one means, reference maybe had to the cited US. Pat. No. 3,355,000.

It is apparent that the slowing and controlling effect of spring 172 isexercised at the latest possible portion of the typebar stroke and thattherefore the effective average speed of the typebar 155 may be greaterthan in a structure which introduces the slowing effect at an earlierportion of the stroke of the typebar 155.

At least some of the energy stored in spring 172, just prior to printingimpact, is returned to the typebar 155 after printing to accelerate thereturn of the typebar 155 to its rest position. The fact that thetypebar 155 is accelerated so soon after the printing operation alsocontributes to the overall speed increase.

It may be noted that the tension of spring 132 also exercises an effecton the impression. If the tension on spring 132 is increased the impactforce for producing an impression on the document is reduced.Conversely, a reduction in the tension of spring 132 will result in anincrease of the impact force. Accordingly, overall impression controlmay be exercised by adjustment of spring 132. Impression control ofindividual typebars 155 may be obtained by means such as that given inthe cited US. Pat. No. 3,355,000 or by means such as that disclosed inthe copending application of T. H. Toeppen, entitled VARIABLE RADIUSCRANK ARM FOR TYPEWRITER IMPRESSION CONTROL, filed on Jan. 29, 1970, andassigned Ser. No. 6,785.

It may appear that the overall escapement structure could be simplifiedby causing the escapement in response to the operation of the space bar136 to operate through the same linkage as that which operates theescapement when a character is printed. All that would be required wouldbe to eliminate escapement bellcrank assembly 142 and substitutetherefore an assembly including a lever similar to bellcrank lever 106and its operating lever 106a which would be coupled to cam link 141.Although this modification would provide an escapement action, it wouldalso result in a ribbon lift action. Although lifting the ribbon woulddo no particular harm, it might be confusing to the operator.Furthermore, it would also result in an unnecessary ribbon advance whichwould be wasteful if carbon ribbon is being used. Furthermore, in atleast some structure there would be no spare room for the additionalbellcrank lever 106.

Operating lever 106a is connected by a cam link 1410 to a cam assembly(not shown) which is similar to space bar cam assembly 138 and which istriggered in response to the operation of the appropriate keylever. Bythis means the escapement action is driven directly from the power roll140 and thus has little if any effect on typebar speed.

It should be noted that the present structure causes an earlierinitiation of the escapement action than the prior art structure using aU-bar. Since escapement takes place before the printing, it is desirableto initiate the escapement at the earliest possible moment in eachcycle. The structure of the present invention has demonstrated a greatlyreduced tendency to print before the completion of an escapement actioneven when the printing rate is considerably increased. Accordingly, thepresent invention has materially contributed to an overall increase inprinting rate.

While there has been shown and described what is considered at presentto be the preferred embodiment of the invention, modifications theretowill readily occur to those skilled in the related arts. For example, inanother structure various types of friction or clutch devices could beused to provide the required one way linkages and/or the number of linksand levers could be modified to suit the geometry of the structure. Itis believed that no further analysis or description is required and thatthe foregoing so fully reveals the gist of the present invention thatthose skilled in the applicable arts can adapt it to meet the exigenciesof their specific requirements.

What is claimed is:

l. in a typebar printing mechanism:

a. an escapement trip structure coupled to .a shaft and responsive tolimited angular reciprocal rotation of said shaft about its axis forinitiating an escapement action;

b. first and second means for initiating limited angular reciprocalrotation of said shaft;

c. a ribbon lift structure coupled to a pivoted ribbon lift bar andresponsive to the pivoting of said ribbon lift bar for raising a printribbon guided by said ribbon lift structure to a print position;

d. actuating means responsive to each printing cycle of the typebarprinting mechanism for pivoting said ribbon lift bar;

c. said first means comprising a first plurality of coupling linksbetween said shaft and said ribbon lift bar for initiating limitedangular reciprocal rotation of said shaft in response to each pivotingaction of said ribbon lift bar;

f. said second means comprising a second plurality of coupling linksbetween said shaft and an actuator for initiating limited angularreciprocal rotation of said shaft in response to the selective operationof said actuator and without any pivoting action of said ribbon liftbar;

g. said first plurality of coupling links including a one-way drivelinkage for inhibiting the pivoting of said ribbon lift bar in responseto the actuation of said second means; and

h. said second plurality of coupling links including a oneway drivelinkage for inhibiting the actuation of said actuator in response to theactuation of said first means.

1. In a typebar printing mechanism: a. an escapement trip structurecoupled to a shaft and responsive to limited angular reciprocal rotationof said shaft about its axis for initiating an escapement action; b.first and second means for initiating limited angular reciprocalrotation of said shaft; c. a ribbon lift structure coupled to a pivotedribbon lift bar and responsive to the pivoting of said ribbon lift barfor raising a print ribbon guided by said ribbon lift structure to aprint position; d. actuating means responsive to each printing cycle ofthe typebar printing mechanism for pivoting said ribbon lift bar; e.said first means comprising a first plurality of coupling links betweensaid shaft and said ribbon lift bar for initiating limited angularreciprocal rotation of said shaft in response to each pivoting action ofsaid ribbon lift bar; f. said second means comprising a second pluralityof coupling links between said shaft and an actuator for initiatinglimited angular reciprocal rotation of said shaft in response to theselective operation of said actuator and without any pivoting action ofsaid ribbon lift bar; g. said first plurality of coupling linksincluding a one-way drive linkage for inhibiting the pivoting of saidribbon lift bar in response to the actuation of said second means; andh. said second plurality of coupling links including a one-way drivelinkage for inhibiting the actuation of said actuator in response to theactuation of said first means.